Thermoplastic Ball Valves 1/2" - 4" are designed to safely block full system pressure in either direction to allow on-line system maintenance. Valve stem is of the blow-out proof design. Valve has full port for lowest possible pressure loss. Seats shall be easily adjustable and replaceable. Stem has an internal pressure sealed land to protect stem and stem seal from contaminants. Every valve is fully pressure and cycle tested before leaving the factory.